New York City would spiral into a crime-ravaged nightmare, unsafe for both civilians and law enforcement, should socialist Zohran Mamdani become mayor, Mayor Adams forewarned.

Mayor Adams cautioned that the radical Democratic mayoral candidate’s anti-police and lenient crime policies would undo the progress he’s made in reducing significant crime rates during his term, during a private discussion on the patio of Gracie Mansion.

“Consider [Mamdani’s] strategies: emptying Rikers Island would have a substantial impact,” he told The Post, referencing Mamdani’s proposal to significantly reduce the jail’s population of 7,600. “The crime will simply return to the neighborhoods it originated from.”

Adams, a retired NYPD captain, said Mamdani’s plan to have social workers respond to domestic violence calls — rather than cops — is another recipe for disaster.

He referred to NYPD Officer Wilbert Mora, 27, and his rookie partner Jason Rivera, 22, who were shot dead by 47-year-old Lashawn McNeil on Jan. 21, 2022 in East Harlem.

“Mora and Rivera, the two cops who were shot in the beginning of my [mayoral] career, they died and were assassinated responding to a domestic violence call,” said Adams, whose voice cracked with emotion while delivering eulogies at memorial services for the men days later.

“I think that we’re going to see some real errors” if Mamdani is elected mayor, Adams said. “His policies are harmful to the city.”

During a wide-ranging interview, Adams, sporting a gray pinstripe suit, black loafers and a silver watch, insisted he’s had to waste too much time in office “cleaning up” a “mess” he inherited thanks to state bail reform laws and other left-wing policies implemented under former Gov. Andrew Cuomo, a registered Democrat who like Adams is also running for mayor as an independent.

He also insisted a bombshell lawsuit filed this week by former top cop Tom Donlon accusing him of running the NYPD like a criminal enterprise is both “baseless” and “politically” motivated — and that he has a great working relationship with current Police Commissioner Jessica Tisch, who he wants back if he’s reelected.

“She’s the commissioner as long as she wants to [be],” said Adams. “I’m excited about the work that she’s doing.”

He praised her for coming up with the “brilliant” ideas of implementing “Q-Teams” to crack down on quality-of-life offenses and deploying extra cops to notorious crime hot spots.

When asked if he plans to use his administration’s rising star to help score support with voters, Adams said Tisch “has already been a great spokesperson,” but warned “you can’t cross the line.”

“She’s driving down crime, and whenever she has an opportunity, she makes it clear that this mayor has supported the law enforcement community and police,” he said.

Mamdani, Adams and Cuomo are part of a crowded field heading into November’s mayoral election that also includes Republican nominee Curtis Sliwa.

All but Mamdani are targeting the same moderate and conservative voters, making the 33-year-old socialist the clear frontrunner heading into November’s general election as he’d benefit greatly from this voting base being split on who to support.

Except Mamdani, all the candidates have made improving public safety a major platform of their campaign, but Adams — who was elected mayor in 2021 by promising to drive down crime — insisted he’s the only one with the track record to deliver.

“First of all, Curtis doesn’t have a record,” Adams said. “Andrew Cuomo is running from his record. Bail reform. I had to fix that. Cannabis Law. I had to fix that. Raise the Age [a law ending the automatic prosecution of 16- and 17-year-olds as adults]. I had to fix that.

“You look at my record, and then you compare it to his record. I had to fix his mess. He created a mess for our city, and I got to fix it.”

Adams also said he’s not concerned the other candidates had a head start campaigning and that he’s entering the race’s final months as an underdog.

“When you look at the lawfare that I experienced for 15 months, you’re being pounded for 15 months, you know,” said Adams, referring to now-dropped federal corruption changes that led to him deciding not to run in last month’s Democratic primary.

“It’s amazing that people still at all say, ‘Hey, we want to be with this mayor,’” he said. “And they never knew my story. Now I have the opportunity to use my campaign dollars to speak to the [voters]. I’m now able to tell my story that has not been told for three years and seven months.”

Mamdani did not return messages, but both Cuomo’s camp and Sliwa cited the Donlan lawsuit as one of many reasons why they believe Adams must be replaced.

“Ask anyone in this city, and they’ll tell you they don’t feel safe because they aren’t,” said Sliwa, founder of the Guardian Angels crime-prevention group.

“No one is buying what [Adams] is selling,” said Cuomo spokesman Rich Azzopardi.

Despite all the gloom and doom Adams painted for Gotham if Mamdani becomes mayor, Adams said he has no desire to move from NYC — even if it’s led by a socialist.

“I’m a New Yorker,” he said. “I’m going to continue to stay here and fight for the city. The city’s worth fighting for.”